The present proposal represents a pilot project to develop nonradiolabeled DNA probes for the specific detection of varying levels of Streptococcus mutans in human saliva. It is likely that such probes could be useful in diagnostic kits to identify children at high risk of dental caries. Identification of such individuals by a highly specific and simple diagnostic test should result in effective prophylactic treatment to further reduce the incidence of dental caries. Biotinylated DNA fragments from the gtfB gene of S. mutans GS5 will be isolated and examined for specificity following dot-blotting of chromosomal DNA from a panel of oral microorganisms. Synthetic oligonucleotides will be prepared from the known sequences of the specific probes for testing with human salivary samples. Detection of varying levels of S. mutans in saliva will be compared utilizing the probes and the standard bacteriological sampling procedure. Based on recent results it is likely that specific S. mutans probes can be developed for subsequent utilization in diagnostic kits.